Flow Assurance Technical Section

Any guidance on the following would be much appreciated.

Looking to understand defoamer concentration value in a gas well.  I have found a fair bit of literature for defoamer concentrations for oil production wells where the defoamer amount is based off the liquid volume but unsure in the case we have with a predominantly gas and water well.

The well has a foaming agent added downhole to help lift the water to surface where a defoamer(antifoam) is  added to the combined gas/liquid/foam stream before entering into the separator where it is allowed to settle before the various fluid streams exit into their respective gathering system.

I was concerned about the volume of antifoam we are using, so I've calculated the ppm  of antifoam to the total liquid volume being produced for two of our wells (details below). The gas volume has not been included in my calc. 

Have i done this correctly? Is this the calculation and values i should be using when trying to understand how much defoamer to be used.  As from the calculation it seems we are using far to much, and that we should be targeting values between 50-300ppm of defoamer of the total liquid volume.

The gas is 100% methane, there are no liquid hydrocarbons. 

	Gas rate (scm/d)	Water (liters/d)	Foaming Agent (L/d)	Antifoam Agent (L/d)	Antifoam/Foam Ratio	Total Fluid (L)	Anti Foam of Total Liquid (fraction)	Anti Foam Concentration (ppm)
Well 1	16,700	14,400	125	17	13.60%	14,542	0.001169	1,169
Well 2	50,000	8,640	120	22.5	18.80%	8,783	0.0025619	2,562

thanks for any guidance

Humm

I love using foamers for gas wells for deliquification but it has its own quirks and requires a holistic approach to solve the problem.

For this discussion I will use FA (foaming agents) and AF (antifoam), so it faster to type.

The goal here, is to put enough FA downhole to bring up all the liquids and make it sure it breaks in the flowline BEFORE it hits the separator. It would seem your description, your foam is stable at the separators, which usually means your FA concentration is probably too high for the well.

It would be best to focus on optimizing the FA concentration downhole for each well first. (This is easy to do, but it takes time and patience). Maximize gas rate rate with the lowest FA concentration when testing with your test separator or wellhead temperature. (3-4 of points will do). The lowest FA rate will give you the best chance the foam breaks in the flowline before it gets to the separator. (but again this depends on the individual well gas rate, condensate, water, solids, mineral concentrations, depth of injection etc…). Solids t(even in small quantaties) tend to stabilize foam extremely well.

If you need AF, its better to inject it in smaller quantities at the wellhead, so it breaks before it gets to the separator.
(You need much larger volumes of AF for separator injection)

I know this advice did not give you the answer you wanted to hear but foam is notoriously difficult to break when using FA agents. Because you have multiple streams of wells entering the manifold, the mixture tends to stabilize foam even better than the individual wells (difference in gas, condensate, water, solids, mineral concentrations etc…). Unstable foam tends to muck up the entire facilities, so we tend to overdose with AF and then we create and unending cycle of problems and cost.

------------------------------
Basker Murugappan
Principal Production Technologist
Villalbilla, Spain
+34 644485970

Three basic rules:
1) Change is inevitable.
2) Everybody resists change.
3) You cant stop change
------------------------------

Thanks for the input there Basker, much appreciated.  Tallies with what others have been sayings as well to focus on the foamer concentration first.  The focus on the Anti-foam had been driven by the cost of it compared to the cost of the foamer so on first glance there quicker savings there but as you point out, you're best off trying to stop making so much foam in the first place rather than trying to destroy it more efficiently once you've made it!

Original Message:
Sent: 04-05-2023 02:50 AM
From: Basker Murugappan
Subject: Defoamer Concentration in gas well

Humm<o:p></o:p>

I love using foamers for gas wells for deliquification but it has its own quirks and requires a holistic approach to solve the problem.<o:p></o:p>

For this discussion I will use FA (foaming agents) and AF (antifoam), so it faster to type.<o:p></o:p>

The goal here, is to put enough FA downhole to bring up all the liquids and make it sure it breaks in the flowline BEFORE it hits the separator. It would seem your description, your foam is stable at the separators, which usually means your FA concentration is probably too high for the well.

<o:p></o:p>

It would be best to focus on optimizing the FA concentration downhole for each well first. (This is easy to do, but it takes time and patience). Maximize gas rate rate with the lowest FA concentration when testing with your test separator or wellhead temperature. (3-4 of points will do). The lowest FA rate will give you the best chance the foam breaks in the flowline before it gets to the separator. (but again this depends on the individual well gas rate, condensate, water, solids, mineral concentrations, depth of injection etc…). Solids t(even in small quantaties) tend to stabilize foam extremely well.<o:p></o:p>

If you need AF, its better to inject it in smaller quantities at the wellhead, so it breaks before it gets to the separator.
(You need much larger volumes of AF for separator injection)<o:p></o:p>

I know this advice did not give you the answer you wanted to hear but foam is notoriously difficult to break when using FA agents. Because you have multiple streams of wells entering the manifold, the mixture tends to stabilize foam even better than the individual wells (difference in gas, condensate, water, solids, mineral concentrations etc…). Unstable foam tends to muck up the entire facilities, so we tend to overdose with AF and then we create and unending cycle of problems and cost.<o:p></o:p>

------------------------------
Basker Murugappan
Principal Production Technologist
Villalbilla, Spain
+34 644485970

Three basic rules:
1) Change is inevitable.
2) Everybody resists change.
3) You cant stop change
------------------------------